dogs have been chewing up and eating leather as long as leather has been made. once in a while I'm sure it doesn't go well. kind of like the person that chokes on a piece of chicken and dies, one in a million. Now man made stuff like Kgg is talking is a different story altogether I had a black lab that couldn't pass a bunch of foam from a seat cushion she ate and needed help, she about died. i have four dogs none eat leather one used to bite the leashes in half to get loose, they all eat wood and will shred 4" logs just from nervous energy. except for my Beagle she shreds small sticks lol. One thing i have learned from my wood chewers is carrots will suffice for the nervous habit and is very safe for them to chew up. My dogs love carrots lol go through a bag a week. I love dogs!